Solid combination really, ccleaner and malwarebytes are nice to have together with any solid anti-virus. Just make sure to not use any conflicting software with them (make sure that your firewall+windows defender is disabled, don't use any of the programs below with norton installed).

Norton used to be shitty long ago but have improved a lot over the last few years so you should have no problems with that setup (it's more pricy despite not being better than all other options though). I'm personally using f-secure (I used to work there so I know the program inside out) which is one of the better programs. Another solid (arguably the best) anti-virus is kaspersky. Just stay away from scams like mcafee and avg (both are obnoxious programs, mcafee takes the cake though) and you'll generally be fine.

Note: My rankings above are based on what I knew two years ago since I haven't bothered looking into them after I quit my work, may very well be incorrect these days.

I'm not using any. Can't help you there. Would not recommend using Avast though, it makes older computers inoperable due to the frantic scanning of everything so i'm pretty sure it has a performance impact on any new system aswell.

Paid for AV's aren't necessarily in the business of preventing viruses --- In order to keep buying the latest and greatest, there was to be demand caused by imminent threat. Best AV's are the free ones like mentioned above. Safe web practices cannot be beat as well.

I'm not using any. Can't help you there. Would not recommend using Avast though, it makes older computers inoperable due to the frantic scanning of everything so i'm pretty sure it has a performance impact on any new system aswell.

I've seen a fair few anti-virus programs and Avast is definitely one of the least of the frantic scanners, the worst ones I've seen for background scanning are Microsoft Security Essentials and Norton but it does definitely also depend on what other processes you have running. There's a certain printer driver I know for example that triggers some AV software into a constant scan loop, uninstall the driver and the scanning stops.

In order to keep buying the latest and greatest, there was to be demand caused by imminent threat.

Sadly many of these imminent threats are created by insiders of the AV software companies themselves, this is basically how the AV industry got bootstrapped into existence in the first place.

Notice how much of the malware in the wild is non-destructive compared to stuff that corrupts all your data. They want you to buy anti-virus software, blowing up your hard disc wouldn't be in their best interests.

Hasn't been anything wrong with norton (it's significantly better than most of the suggestions here) for a lot of years. That it used to be very heavy about 8 years ago is true, not anymore though.

Good thing colwraith mentioned RKill, really useful program if you happen to get infected after all, especially by rogue security software. Not really something you run if everything is working properly though.